BEIJING — “Bodybuilder” pigs given illegal growth hormones in their feed. Harmful additives to make pork taste like beef. Outdated steamed buns painted with coloring to look new. Formaldehyde in a popular Sichuan dish. Exploding watermelons that had been treated with plant growth chemicals.

These are just some of the many food scares in China in recent days and weeks that have made local newspaper headlines and caused growing anxiety — and anger — among Chinese consumers about the quality of what they eat and drink.

“I’m really worried about food safety,” said Li Suhua, 57, who is retired and was shopping for her family recently at a fruit and vegetable market. She said she comes to the market two or three hours before she starts cooking, to give herself time to soak leafy green vegetables to rid them of pesticides. As for meat, she said, “I’m even more worried. We haven’t eaten chicken for a long time, because I heard they gave hormones to chickens.”

“It’s really horrifying,” she said.

The safety of the food supply has been a public worry here since a 2008 scandal over melamine-tainted milk and infant formula that left six children dead from kidney damage and 300,000 people ill. Many new parents buy only imported milk powder for their children, or get infant formula online, or buy it during trips to Hong Kong or Japan.

Now, food safety has become a top priority for the Chinese government, which in the past was more concerned about food security — having enough for people to eat. Vice Premier Li Keqiang, who is slated to become prime minister in a leadership reshuffle next year, has taken charge of the campaign to improve the safety of food.

That, in turn, has sparked an aggressive kind of investigative reporting in the government-controlled media that is rarely applied to other aspects of society.

“The top leaders have attached more importance to food safety. That gives the media more freedom to report on it from different angles,” said Zheng Fengtian, an agribusiness professor and vice dean of Renmin University’s agriculture school. “The problem has always been there, but the media didn’t give it much attention before.”

To show its seriousness about the mounting list of problems, Xinhua, the state news agency, reported late last month that the government will offer rewards to informants who provide tip-offs about tainted food and has promised to protect the identity of the tipsters to guard against “revenge attacks.” According to a new edict, “Government departments at all levels must set up dedicated funds for a reward system for reporting on food safety,” Xinhua said.

A Web site called Throw it out the Window, which tracks food safety scandals across the country, has reported 494 cases of food contamination this year. The site, started in June by a fed-up 25-year-old graduate student and a group of 33 volunteers, has recorded 2,230 cases since 2004.

The U.S. Food and Drug Administration also has officials working on the ground in China, increasing inspections of Chinese firms that export products to the U.S. market and helping China build “technical capacity” to improve its food safety regime.

And just why are there so many food problems in China? The answers, expert said, are complex, involving China’s system of myriad tiny farms, tens of thousands of small food-processing factories scattered across this vast country, and a regulatory system in which enforcement is divided among as many as 13 government ministries and departments.

“Each department is only responsible for a certain cycle, such as cultivation, production or sales,” said Wu Yongning, chief scientist for food safety at the Ministry of Health. “It’s really difficult to control risk with this multi-layered management.”

Said Zheng, the Renmin University professor: “It’s a long distance from the field to the mouth.”

In addition, experts said, despite a number of high-profile busts, the chances of getting caught and punished for producing or selling tainted food remains relatively small.

In many of the cases, particularly those involving pesticides and other chemicals, experts said the rural farmers often do not understand the harmful effects on humans. For example, the case of exploding watermelons in Jiangsu province in May was thought to be at least partially caused by farmers’ overuse of a plant growth accelerator called forchlorfenuron.

In Sichuan this year, police acting on a tip arrested a father and son whose company made xiewang, a local delicacy known as “bloody tofu” made of congealed duck or pig’s blood. The pair told police that they had been adding formaldehyde to their produce to make it smoother and extend its shelf life, according to local media reports. Formaldehyde can cause brain, colon and nose tumors in humans.

At times, the addition of dangerous chemicals is more malfeasance than ignorance.

A well-known Shanghai steam bun producer in April was found to be adding chemical sweeteners and yellow coloring to buns that were past their “sell by” date, repackaging them as new and re-selling them. Several managers at the bun company were arrested, and four Shanghai officials were disciplined for “dereliction of duty” for failing to detect the scam.

The most recent scandal with pigs involves an additive called clenbuterol, known as “lean meat powder,” used to burn fat and accelerate muscle-building in swine — creating what became known here as “bodybuilder pigs.” The substance was found in pigs in Henan province. The chemical can cause illness in humans if ingested through the pig’s meat.

Journalists in Anhui province also reported finding markets using a harmful food additive to change the appearance and taste of pork to make it seem like beef. A reporter used the additive, called “beef extract,” and found that it took just a few minutes to alter the taste. The markets were selling the “fake beef” for twice the cost of pork.

The sheer number of recent scandals has led many in China to question whether the country is facing a moral and ethical crisis as much as a food safety one — and why the push for slightly higher profits would prompt some people involved in the food chain to heedlessly endanger the health of humans. President Hu Jintao and Premier Wen Jiabao have decried the lack of ethics among food producers.

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